The present invention relates to a workpiece positioning device for a processing center, in particular a horizontal processing center, a processing center comprising such a workpiece positioning device, and a method for positioning a workpiece in a processing center.
In particular in the processing of large parts such as, for example, in tool making, mold making and model making, or in the production in the automobile industry, aerospace industry and in comparable applications in which complex surfaces of large workpieces are to be produced with high surface quality and at high processing speeds, it is common to mount and arrange the workpiece raw parts on a palette and to subsequently move the workpiece palette with the workpiece to the processing unit of a machine tool or to a processing station of a processing center for processing. After processing, the workpiece palette with the processed workpiece is again removed from the processing unit or processing station and transported to a storage area intended for this purpose. To do so, different transport systems, in particular motor-driven linear axles, are used to transport the workpiece palettes between a setup station, a place of processing and potential storage areas and to position them there.
In particular in horizontal processing machines or in horizontal processing centers comprising a horizontally held processing spindle that can be spatially moved and fixed in any pivoting position, e.g., a milling spindle, the palette with the workpiece must be transferred out of a horizontal position on a deposit place of a setup station or a buffer station into a vertical position that corresponds to the processing position or is shifted into said position. To do so, a palette pivoting or swiveling device is necessary that accomplishes the swiveling or pivoting of the palette from the horizontal position into the vertical position and vice versa. For this purpose, it is conventional to use, e.g., palette rotating devices comprising two rotatable gripping arms, or those based on the use of pneumatic or hydraulic cylinders. In the case of very large and heavy workpieces that require an appropriately robust workpiece palette as carrier, the weight of the palette with the workpiece may be several tons, for example, up to 10 tons or even more. The spatial dimension of the palette with the workpiece may also be enormous. Any appropriate palette rotating or palette pivoting device must thus be designed so as to be extremely large and robust and be able to produce extremely great torques. Considering the weight of the workpiece palette mentioned hereinabove, torques within the range of 30,000 to 40,000 Nm may be required on each side of the palette.
Such a palette rotating or palette pivoting device may be extremely difficult to implement and be very expensive. Furthermore, the workpiece palette must frequently be moved into and out of the processing station with an additional linear movement, and, optionally, be raised or lowered for suitable processing or storage positions, so that, in addition to the rotating or pivoting device, motor-driven linear axles are required. Considering the processing of large parts, this results in hybrid transport and positioning devices that are highly complex, bulky and require a large footprint, as well as difficult to handle, such devices involving high costs for acquisition and maintenance.
Considering this, it is the object of the invention to overcome the disadvantages of prior art and provide a new workpiece positioning device for a processing center that is suitable, in particular, for processing large parts, said device including horizontal processing centers. In particular, it is the object of the present invention to provide a workpiece positioning device, a processing center and a method for positioning a workpiece in a processing center that allow a positioning of workpieces, in particular large workpieces, while said workpieces can be pivoted with simple means.
This object is achieved with the workpiece positioning device for a processing center exhibiting the features of claim 1, a processing center according to claim 15, and a method for positioning a workpiece mounted on a workpiece palette in a processing center according to claim 18. Particularly advantageous embodiments of the invention are the subject manner of the dependent claims.